Maximize WPF Window on the current screen

Question

I have a windowless wpf application, whenever I set the window state as maximized it maximizes it on the primary display.

What I would like to do is have it maximize on

Answer 1

A question with 7 upvotes deserves the correct answer. :D

Use this window instead of normal window and then Maxmize/Minimize/normalize will take care of itself.

using System;
using System.Runtime.InteropServices;
using System.Windows;
using System.Windows.Interop;

public partial class MyWindow : Window
{
    public MyWindow ()
    {
        this.InitializeComponent();

        this.SourceInitialized += this.OnSourceInitialized;
    }

    #endregion

    #region Methods

    private static IntPtr WindowProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
    {
        switch (msg)
        {
            case 0x0024:
                WmGetMinMaxInfo(hwnd, lParam);
                handled = true;
                break;
        }
        return (IntPtr)0;
    }

    private static void WmGetMinMaxInfo(IntPtr hwnd, IntPtr lParam)
    {
        var mmi = (MINMAXINFO)Marshal.PtrToStructure(lParam, typeof(MINMAXINFO));

        // Adjust the maximized size and position to fit the work area of the correct monitor
        IntPtr monitor = MonitorFromWindow(hwnd, (int)MonitorFromWindowFlags.MONITOR_DEFAULTTONEAREST);

        if (monitor != IntPtr.Zero)
        {
            var monitorInfo = new MONITORINFO();
            GetMonitorInfo(monitor, monitorInfo);
            RECT rcWorkArea = monitorInfo.rcWork;
            RECT rcMonitorArea = monitorInfo.rcMonitor;
            mmi.ptMaxPosition.x = Math.Abs(rcWorkArea.Left - rcMonitorArea.Left);
            mmi.ptMaxPosition.y = Math.Abs(rcWorkArea.Top - rcMonitorArea.Top);
            mmi.ptMaxSize.x = Math.Abs(rcWorkArea.Right - rcWorkArea.Left);
            mmi.ptMaxSize.y = Math.Abs(rcWorkArea.Bottom - rcWorkArea.Top);
        }

        Marshal.StructureToPtr(mmi, lParam, true);
    }

    private void OnSourceInitialized(object sender, EventArgs e)
    {
        var window = sender as Window;

        if (window != null)
        {
            IntPtr handle = (new WindowInteropHelper(window)).Handle;
            HwndSource.FromHwnd(handle).AddHook(WindowProc);
        }
    }
}

DLL imports and declarations

[StructLayout(LayoutKind.Sequential)]
public struct MINMAXINFO
{
    public POINT ptReserved;

    public POINT ptMaxSize;

    public POINT ptMaxPosition;

    public POINT ptMinTrackSize;

    public POINT ptMaxTrackSize;
} ;

public enum MonitorFromWindowFlags
{
    MONITOR_DEFAULTTONEAREST = 0x00000002
}

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
public class MONITORINFO
{
    public int cbSize = Marshal.SizeOf(typeof(MONITORINFO));

    public RECT rcMonitor;

    public RECT rcWork;

    public int dwFlags;
}

[StructLayout(LayoutKind.Sequential, Pack = 0)]
public struct RECT
{
    public int Left;

    public int Top;

    public int Right;

    public int Bottom;

    public static readonly RECT Empty;

    public int Width
    {
        get
        {
            return Math.Abs(this.Right - this.Left);
        } // Abs needed for BIDI OS
    }

    public int Height
    {
        get
        {
            return this.Bottom - this.Top;
        }
    }

    public RECT(int left, int top, int right, int bottom)
    {
        this.Left = left;
        this.Top = top;
        this.Right = right;
        this.Bottom = bottom;
    }

    public RECT(RECT rcSrc)
    {
        this.Left = rcSrc.Left;
        this.Top = rcSrc.Top;
        this.Right = rcSrc.Right;
        this.Bottom = rcSrc.Bottom;
    }

    public bool IsEmpty
    {
        get
        {
            // BUGBUG : On Bidi OS (hebrew arabic) left > right
            return this.Left >= this.Right || this.Top >= this.Bottom;
        }
    }

    public override string ToString()
    {
        if (this == Empty)
        {
            return "RECT {Empty}";
        }
        return "RECT { left : " + this.Left + " / top : " + this.Top + " / right : " + this.Right + " / bottom : " +
               this.Bottom + " }";
    }

    public override bool Equals(object obj)
    {
        if (!(obj is RECT))
        {
            return false;
        }
        return (this == (RECT)obj);
    }

    public override int GetHashCode()
    {
        return this.Left.GetHashCode() + this.Top.GetHashCode() + this.Right.GetHashCode() +
               this.Bottom.GetHashCode();
    }

    public static bool operator ==(RECT rect1, RECT rect2)
    {
        return (rect1.Left == rect2.Left && rect1.Top == rect2.Top && rect1.Right == rect2.Right &&
                rect1.Bottom == rect2.Bottom);
    }

    public static bool operator !=(RECT rect1, RECT rect2)
    {
        return !(rect1 == rect2);
    }
}
[DllImport("user32.dll", SetLastError = true)]
public static extern bool GetMonitorInfo(IntPtr hMonitor, MONITORINFO lpmi);

[DllImport("user32.dll", SetLastError = true)]
public static extern IntPtr MonitorFromWindow(IntPtr handle, int flags);